Control schemes for haptic feedback interface devices

ABSTRACT

A method is disclosed that includes outputting haptic feedback based on a movement of an object in a first direction from a first position to a second position. The haptic feedback is discontinued when the object is moved in a second direction opposite the first direction subsequent to the movement in the first direction. The haptic feedback is output again when the object moves past the second position in the first direction.

STATEMENT OF RELATED APPLICATION(S)

The present application is a divisional of U.S. patent application Ser.No. 10/895,982, entitled “Hybrid and Resistive Haptic Effects,” filed onJul. 22, 2004 which claims priority to U.S. Patent Application No.60/533,129, entitled “Hybrid and Resistive Haptic Effects,” filed onDec. 30, 2003.

TECHNICAL FIELD

The present disclosure relates generally to control schemes for hapticfeedback interface devices, and more particularly to resistive andhybrid actuator control schemes for haptic feedback interface devices.

BACKGROUND

Haptic feedback interface devices are used for a variety of differentfunctions and are often used with a variety of computer systems. Forexample, haptic feedback interface devices are used with computercontrolled simulations, games, and other application programs. Acomputer system typically displays a graphical environment to a user ona display screen or other output device. The user can interact with thedisplayed environment to play a game, experience a simulation or“virtual reality” environment, or otherwise influence events or imagesdepicted on the screen or in an application program or operating system.Such user interaction can be implemented through an interface device,such as a joystick, “joypad” button controller, mouse, trackball, stylusand tablet, foot or hand pedals, control knob, touch panel, etc., thatis connected to the computer system. The computer updates the graphicaldisplay in response to manipulation of the interface device and provideshaptic feedback based on manipulation and/or movement of the object.Examples of such interface devices are disclosed in U.S. applicationSer. No. 10/285,450, entitled “Method and Apparatus for ProvidingTactile Sensations,” which is incorporated herein by reference in itsentirety.

The haptic feedback provided by the interface device is often output viaactuators in the interface device. These actuators typically includeeither an active actuator or a resistive actuator, depending upon thedesired haptic effect. In addition, interface devices exist that includeboth resistive and active actuators (i.e., hybrid interface devices).Such interface devices, however, often use the different types ofactuators to output feedback that is actuator dependent. In other words,the resistive actuator is used to output one type of feedback and theactive actuator is used to output a different type of feedback.

A need exists, however, for improvements in interface devices andcontrol schemes for interface devices that use resistive and activeactuators to produce desired haptic effects.

OVERVIEW

A method is disclosed that includes outputting haptic feedback based ona movement of an object in a first direction from a first position to asecond position. The haptic feedback is discontinued when the object ismoved in a second direction opposite the first direction subsequent tothe movement in the first direction. The haptic feedback is output againwhen the object moves past the second position in the first direction.

In other embodiments, a device is disclosed that includes an objectdisplaceable in at least one degree of freedom with respect to a firstreference point. A sensor is configured to output a position signalassociated with a displacement of the object, the displacement being oneof a first displacement, a second displacement and a third displacement.An actuator is configured to output a resistive force based on theposition signal, the resistive force being associated with the firstdisplacement of the object in a first direction away from the firstreference point until the object is moved to a position. The resistiveforce is discontinued when the position signal is associated with thesecond displacement in a second direction opposite the first direction.The resistive force is further output after the third displacement inthe first direction past the position, subsequent to the object beingmoved in the second direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a haptic feedback interfacedevice according to an embodiment.

FIG. 2 is an illustration of a device according to an embodiment.

FIG. 3 is an illustration of a force profile associated with a controlscheme according to an embodiment.

FIG. 4 is an illustration of a force profile associated with a controlscheme according to a further embodiment.

FIG. 5A is an illustration of a force profile associated with a controlscheme for a hybrid interface device according to an embodiment.

FIG. 5B is an illustration of a force profile associated with a controlscheme for a hybrid interface device according to an embodiment.

FIG. 6A is an illustration of a force profile associated with a controlscheme associated with direction-dependent detents for a hybridinterface device according to an embodiment.

FIG. 6B is an illustration of a force profile associated with a controlscheme associated with direction-dependent detents for a hybridinterface device according to another embodiment.

FIG. 7 is a schematic representation of a hybrid interface deviceaccording to an embodiment.

FIG. 8 is a schematic representation of a hybrid interface deviceaccording to another embodiment.

FIG. 9A is an actuator command associated with a force profile of aninterface device without demagnetization.

FIG. 9B is the actuator response of the interface device based on theactuator command shown in FIG. 9A.

FIG. 9C is an actuator command associated with demagnetization of aninterface device according to an embodiment.

FIG. 9D is the actuator response of the interface device based on theactuator command shown in FIG. 9C, including a demagnetization pulse.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 is a schematic representation of an interface device 10 accordingto an embodiment. The interface device 10 includes a manipulandum or anobject 20 that is coupled to a sensor 25 and is movable in at least onedegree of freedom. The sensor 25 is configured to output sensor signalsto a microcontroller 27. The microcontroller 27 outputs signals to anactuator 40 based on at least one of the position, velocity, direction,force, torque and acceleration of the object 20.

In some embodiments, the microcontroller 27 includes a processor 30having a processor readable medium 35. The processor 30 is configured toreceive signals from the sensor 25, and output signals to the actuator40. The processor 30 can be, for example, a commercially availablepersonal computer, or a less complex computing or processing device thatis dedicated to performing one or more specific tasks. For example, theprocessor 30 can be dedicated to providing an interactive virtualreality environment.

The processor 30, according to one or more embodiments, can be acommercially available microprocessor. Alternatively, the processor 30can be an application-specific integrated circuit (ASIC) or acombination of ASICs, which are designed to achieve one or more specificfunctions, or enable one or more specific devices or applications. Inyet another embodiment, the processor 30 can be an analog or digitalcircuit, or a combination of multiple circuits.

In some embodiments, the processor 30 includes the processor readablemedium 35. The processor readable medium 35 can include one or moretypes of memory. For example, the processor readable medium 35 caninclude a read only memory (ROM) component and a random access memory(RAM) component. The processor readable medium 35 can also include othertypes of memory that are suitable for storing data in a form retrievableby the processor 30. For example, electronically programmable read onlymemory (EPROM), erasable electronically programmable read only memory(EEPROM), flash memory, as well as other suitable forms of memory can beincluded within the processor readable medium 35. The processor 30 canalso include a variety of other components, such as for example,co-processors, graphics processors, etc., depending upon the desiredfunctionality of the interface device 10.

The processor 30 is in communication with the processor readable medium35, and can store data in the processor readable medium 35 or retrievedata previously stored in the processor readable medium 35. Thecomponents of the processor 30 can communicate with devices external tothe processor 30 by way of an input/output (I/O) component (not shown inFIG. 1). According to one or more embodiments, the I/O component caninclude a variety of suitable communication interfaces. For example, theI/O component can include, for example, wired connections, such asstandard serial ports, parallel ports, universal serial bus (USB) ports,S-video ports, local area network (LAN) ports, small computer systeminterface (SCSI) ports, and so forth. Additionally, the I/O componentcan include, for example, wireless connections, such as infrared ports,optical ports, Bluetooth™ wireless ports, wireless LAN ports, or thelike.

The processor 30 is configured to receive signals from the sensor 25 andoutput signals to the actuator 40. The processor 30 receives data valuesassociated with the position, orientation, movement, velocity,acceleration, etc. of the object 20. In alternative embodiments,multiple sensors (not shown) can be used to determine the state of theobject 20. In some embodiments, the sensors can detect multiple degreesof freedom of the object (e.g., translation, pitch, yaw, rotation,etc.). Interface device 10 can be implemented such that the object 20is, for example, a joystick, trackball, mouse, game controller, knob,wheel, button, etc.

Several control schemes are useful to control the output of hapticfeedback from the interface device 10 via particular actuator and objectconfigurations. In one embodiment, for example, the object 20 is a knobor wheel and a control scheme is provided to output simulated detentforce profiles. Haptic feedback effects for knobs are disclosed in U.S.patent application Ser. No. 10/641,243, entitled “Haptic FeedbackEffects for Control Knobs and Other Interface Devices,” which isincorporated herein by reference in its entirety.

In one embodiment, control schemes are used in conjunction with aresistive actuator to provide a desired haptic effect. An actuator 40 isprovided for each object 20 that includes haptic feedback functionality.In some embodiments, additional actuators can be provided for eachdegree of freedom of object 20. Actuator 40, can be an active actuator,such as a linear current control motor, stepper motor,pneumatic/hydraulic active actuator, a torque motor (motor with limitedangular range), voice coil actuator, etc. Passive actuators can also beused, including magnetic particle brakes, friction brakes, orpneumatic/hydraulic passive actuators, and generate a damping resistanceor friction opposite a direction of movement of object 20. Resistiveactuators, as discussed herein, include passive actuators. Activeactuators, as discussed herein, include assistive actuators.

One implementation of a control scheme includes controlling the hapticfeedback based on the velocity of the object 20 (e.g., a knob). In suchan implementation, detents output with resistive actuators can have adrawback when moving at high speeds. The simple position-based detentoutput via resistive actuators provides a sufficiently realistic andacceptable sensation at low speeds. When the object 20 is moved quickly,however, the detents are perceived at a much lower magnitude. One way tocompensate for this effect is to make the magnitude of the detents afunction of the velocity. As the velocity increases, so does the peaktorque of the detents.

Referring to FIGS. 2 and 3, a control scheme according to an embodimentincludes resetting a boundary of a virtual barrier encountered duringmovement of an object 200. The forces output can be, for example,simulated spring forces, and can be associated with an event in agraphical environment. For example, the movement of the object 200 maybe associated with a movement of a graphical object on a display, suchas in a video game. The barrier may include a wall in the same videogame that is contacted by the moving graphical object. In theillustrated embodiment, the object 200 is a knob, but any object movablein at least two directions can be used (e.g., a joystick, a mouse, etc).The forces output by the actuators can also be used in otherapplications, such as a simulated radio tuning knob. When the knobreaches the end of the frequency range of the radio, force is output tosimulate reaching the end of the range. In such an embodiment, the“barrier” is the end of the frequency range of the radio. As the knobcontinues to be turned in that same direction, force will continue to beoutput. When the knob is turned in the opposite direction, back acrossthe range of radio frequencies, the resistive force is discontinued andthe barrier position is reset as discussed above. The force is againoutput when the knob is turned back towards the end of the frequencyrange at the point where the knob engages the reset barrier position.

As the object 200 is moved through various positions, the output of theactuator can be modified. The object starts at position P₀ at a time t₀.As the object 200 is moved in a first direction away from its originalposition P₀ to a second position P₁ at time t₁, no force is output bythe actuator 40. As the object contacts a barrier at the barrierposition P₁, a resistive force is output by the actuator 40 based on themovement and/or position of the object 200 until the object reachesposition P₂ at time t₂. The force that is output during the movement ofthe object 200 from position P₁ at time t₁ to position P₂ at time t₂ canbe a constant resistive force as illustrated in FIG. 3 or a resistiveforce proportional to the distance of penetration into the virtualbarrier (not illustrated).

The haptic feedback is discontinued when the object 200 is moved in thesecond direction opposite the first direction (i.e., when the object ismoved from P₂ at time t₂ to P₁ at time t₃. When the object 200 stops atposition P₁, position P₂ is reset as the position of the barrier. Thus,it is not necessary to move the object 200 back through the previouslypenetrated distance into the barrier. When the object is moved back inthe first direction, from P₁ to P₂, no force is output until the objectreaches the new position of the barrier, P₂, at time t₄. When the object200 reaches position P₂ at time t₄, the resistive force is output untilthe object reaches position P₃. When the object 200 reaches position P₃,the force output can be discontinued if the object is moved back in thesecond direction. Alternatively, the object 200 can continue to be movedin the first direction, thus continuing to output the resistive force.

In an alternative embodiment, haptic feedback can be output when theobject 200 is moved in the second direction (e.g., from P₂ to P₁). Thehaptic feedback that is output when the object 200 is moved in thesecond direction can be different than the haptic feedback associatedwith movement of the object 200 in the first direction. For example, thehaptic feedback associated with the movement of the object 200 in thefirst direction can be a constant resistive force and the hapticfeedback associated with the movement of the object 200 in the seconddirection can be a simulated detent represented by the dashed line inFIG. 3.

In another embodiment, position reset can be accomplished for the outputof a detent. For example, when resistive actuators are used to outputdetent forces, a user will often release the object or manipulandum whenthe object is positioned off the center of the detent. Without positionreset, the first detent output when the object is next engaged is notconsistent with other detent outputs because the object did not start inthe center of the detent. To provide more consistent initial detentinteraction with a resistive actuator, the position of the object isredefined to be the center of the detent after the user has released theobject. The release of the object can be detected in various ways. Forexample, a sensor could be used to detect when contact with the objecthas ended. Alternatively, the center position can be reset after theobject has not been moved for a period of time.

Another implementation of a force profile associated with a controlscheme according to an embodiment includes using a resistive actuator tocreate an assistive sensation. Referring to FIG. 4, the resistiveactuator can be set to output a given level of force. At some point,such as a predetermined location or orientation A₁, or at apredetermined time, the resistive actuator abruptly reduces the amountof force being output to zero, for example, thereby reducing to almostzero the friction on the object. Such an abrupt reduction in the outputforce provides the sensation of an assistive force. When the object 20is moved out of the predetermined location or orientation to anotherlocation or orientation A₂, the resistive force is again output. Thelocations or orientations A₁, A₂ can be associated with simulatedinteractions in a graphical environment or can be time-based.

In another embodiment, control schemes are used in conjunction with aresistive actuator and an active actuator to provide a desired hapticeffect, such as a simulated detent. Interface devices that use bothassistive and resistive actuators can be referred to herein as “hybrid”interface devices.

Examples of force profiles associated with control schemes that can beused with hybrid interface devices to output simulated detent forces areillustrated in FIGS. 5A, 5B, 6A and 6B. Referring first to FIG. 5A, anexample of a force profile associated with a control scheme isillustrated in which an assistive force is continuously output by theassistive actuator and is based on the position of the object. Atpredetermined locations, also based on the position of the object, aresistive force provided by the resistive actuator is superposed on theassistive force. The collective effect from the assistive and resistiveforces provides an enhanced detent sensation.

FIG. 5B illustrates another example of a force profile associated with acontrol scheme in which both assistive and resistive actuators are usedto output a simulated detent force. In the illustrated control scheme,both active and resistive forces are both continuously output based onthe position of the object to obtain the desired detent sensation.

FIGS. 6A and 6B illustrate examples of force profiles associated withcontrol schemes for use with a hybrid device to providedirection-dependent detents. For example, FIG. 6A illustrates an exampleof a force profile associated with a control scheme in which assistiveforces and resistive forces are output in an alternating manner based onthe position of the object. For example, as an object is moved from leftto right, an assistive force will be applied over a certain distance,followed by a resistive force applied over a distance. FIG. 6Billustrates an example of a control scheme in which assistive forces andresistive forces are output in an alternating manner based on theposition of the object. In the illustrated embodiment of FIG. 6B,however, the assistive force is applied in the opposite directionbecause the object is moved in the opposite direction. For example, asthe object is moved from right to left, an assistive force will beapplied over a distance in the direction opposite the direction theassistive force applied when the object is moved from left to right,followed by a resistive force applied over a distance.

Hybrid devices have at least one active actuator and at least oneresistive actuator coupled to the object 20 to provide different forceeffects as described above. Both of these actuators have differentfiltering requirements with respect to the signals generated by thesensor coupled to the object (e.g., position signals, velocity signals,acceleration signals). For the assistive force component of the signal,a balance between the delay and the smoothness of the signal should beachieved. Too much delay in the signal can result in instabilities ofthe device, while too much noise in the signal can result in unwantedtextures that can be perceived by the user. For delay purposes, avelocity signal can be filtered at frequencies of at least approximately100 Hz, for example.

The filtering requirements for the resistive force component aredifferent from the filtering requirements for the assistive forcecomponent. Because the resistive force component of the signals outputby the sensor is inherently stable, the filtering can be much moreaggressive, resulting in a smoother signal. The velocity signal for theresistive component can be low passed at approximately 10 Hz, forexample. Regardless of the particular type of signal and the frequenciesat which the two components are filtered, the active component istypically filtered at a higher frequency than the resistive component.

The signal filtering can be accomplished using various configurations.For example, referring to FIG. 7, one filter 700 can be used. In such aconfiguration, the single filter performs different functions dependingon whether the signal being filtered is associated with the activeactuator 400 or the resistive actuator 450. Alternatively, referring toFIG. 8, two separate filters can be used. One filter 800 is associatedwith the active actuator 400 and another filter 850 is associated withthe passive actuator 450. The different filters 800, 850 performdifferent functions based on the actuator with which they areassociated.

One concern with some embodiments of interface device described hereinis that as the interface device 10 is being used, it can becomemagnetized over time depending on the materials used to construct theinterface device 10. As the actuator is repeatedly actuated, theactuator “sticks” because it becomes magnetized. In other words, theresistive actuator doesn't release quickly enough, thereby creating the“stickiness” discussed above. This is due to residual magnetization,which produces a friction level higher than the base line friction inthe actuator. To improve the resistive actuator performance, theresidual magnetization can be eliminated.

FIGS. 9A and 9B illustrate the actuator command 910 and actuatorresponse 920 of an interface device without demagnetization,respectively. When the actuator command 910 is set to zero after detentsare output, the friction level of the actuator response 920 due to theresidual magnetization is higher than the friction before the detentswere output as illustrated in FIG. 9B.

The interface device can be demagnetized by reversing the polarizationof the magnetic field for successive simulated detents to demagnetizethe interface device (i.e., applying a demagnetization pulse 950). Thestandard method of demagnetization is to apply a decaying sinusoidpulse. In some embodiments, a single pulse is used to demagnetize theactuator. The demagnetization pulse 950 is a negative pulse of certainsize and duration that will improve the demagnetization of the actuator.FIG. 9C illustrates the actuator command 910′ including application ofthe demagnetization pulse 950, and the associated actuator response920′. Once the demagnetization pulse 950 is applied, the friction in theactuator returns to the level it was at before the detents were outputas illustrated in FIG. 9D.

In addition to the polarity of the voltages alternating at eachsubsequent position, the magnitude of the voltage output may vary witheach successive detent. If a given pulse of duration Δ_(t) and magnitudeΔ_(m) demagnetizes the actuator, a pulse of reduced Δ_(t) and increasedA_(m) will work as well. The varying magnitude may be based on theposition of the object with respect to a reference point or originposition. The magnitude may also vary based on the range of motionthrough which the object travels.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of the subject matter should notbe limited by any of the above-described embodiments, but should bedefined only in accordance with the following claims and theirequivalence.

The previous description of the embodiments is provided to enable anyperson skilled in the art to make or use the claimed subject matter.While the subject matter has been particularly shown and described withreference to embodiments thereof, it will be understood by those skilledin art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the inventive subjectmatter.

For example, the desired effects described herein can be accomplished byany combination of resistive and active actuators. For example, althoughcertain effects are described as being accomplished with an activeactuator, the same effect may be accomplished by a resistive actuator ora combination of a resistive actuator and an active actuator (i.e., asin a hybrid interface device).

Although the haptic effect is primarily described as being a simulateddetent in some embodiments, in alternative embodiments the output fromthe interface device can include desired haptic feedback. For example,the haptic feedback can be a vibration, a jolt, a hill, a spring force,a texture, etc.

Although the various force profiles and associated control schemes areprimarily disclosed as being based on the position of the object of thedevice, the various force profiles may also be velocity, acceleration,torque, force, and/or time based.

1. A resistive and active actuator device, comprising: an activeactuator configured to be coupled to an object; a resistive actuatorconfigured to be coupled to the object; and a filter configured tooutput a first filtered signal associated with the active actuator and asecond filtered signal associated with the resistive actuator, the firstfiltered signal and the second filtered signal being different from oneanother.
 2. A method of outputting haptic effects from a knob,comprising: sensing movement of a rotatable knob in a first and seconddirection, wherein the knob is moveable to a plurality of positions;outputting haptic feedback based on a movement of the knob in the firstdirection from a first position to a second position, the hapticfeedback being discontinued when the knob is moved in the seconddirection opposite the first direction subsequent to the movement in thefirst direction; and outputting the haptic feedback when the knob movespast the second position in the first direction, wherein the hapticfeedback changes in magnitude based on a velocity of sensed movement. 3.A method, comprising: outputting via a sensor a signal associated withan active actuator; outputting via the sensor a signal associated with aresistive actuator; filtering the signal associated with the activeactuator using a first filter to produce a first filtered signal;filtering the signal associated with the resistive actuator using asecond filter to produce a second filtered signal; and outputting hapticfeedback based on at least one of the first filtered signal or thesecond filtered signal.
 4. A method, comprising: applying to an actuatorof an interface device a first voltage having a polarity, the actuatorbeing configured to simulate a detent in response to the first voltage;and applying to the actuator a second voltage having a polarity oppositethe polarity of the first voltage, the first voltage and the secondvoltage collectively operative to demagnetize the interface device
 5. Amethod of outputting haptic detents, comprising: receiving a signalassociated with a movement of an object from a first position associatedwith a detent to a second position associated with the detent, thedetent having a center position; outputting a resistive force on theobject based on the signal, the resistive force operative to simulatethe detent; and defining the second position associated with the detentas the center position of the detent.